Methane Bubbling Up From Undersea Permafrost?


19 Dec 2008

The East Siberian Sea is bubbling with methane, a powerful greenhouse gas, being released from underwater reserves, according to a recent expedition.

This could be a sign that global warming is thawing underwater permafrost, which is releasing methane that has been locked away for many thousands of years.

If these methane emissions from the Arctic speed up, it could cause “really serious climate consequences,” said expedition member Igor Semiletov of the University of Alaska, Fairbanks.

(Related: “Global Warming Feedback Loop Caused by Methane, Scientists Say” [August 29, 2006].)

Semiletov and colleagues have traveled along the Siberian coast—this year they covered 13,000 miles (22,000 kilometers)—while monitoring methane concentrations in the air and observing the seas.

“According to our data, more than 50 percent of the Arctic Siberian shelf is serving as a source of methane to the atmosphere,” Semiletov said.

This vast shelf is about 750,000 square miles (2 million square kilometers)—about the same size as Greenland or Mexico—and about 80 percent of it is covered with permafrost, Semiletov said.

He presented the findings from his group at an American Geophysical Union meeting in San Francisco this week.

Not-So-Permanent Permafrost

Permafrost is basically dirt that’s been permanently frozen for hundreds or thousands of years, much of it since the last ice age.

Sea levels back then near the Siberian coast were about 325 feet (100 meters) lower than today, and the exposed ground froze solid down to 1,600 to 2,300 feet (500 to 700 meters) deep.

Over the past 10,000 years, sea levels rose to cover some of this permafrost, and in recent years those seas have seen increases in average temperatures.

“As a result, sub-sea permafrost has warmed up to minus 1 degree Celsius [30 degrees Fahrenheit],” Semiletov said. “It’s very, very close to the thawing point.”

Underneath the permafrost are stores of methane, the same as the natural gas people use for cooking and heating.

© 1996-2009 National Geographic Society. All rights reserved.

bookshelf

books I've read on failure & grace

The World Without Us
The Last Oil Shock: A Survival Guide to the Imminent Extinction of Petroleum Man
Zeitoun
A Paradise Built in Hell: The Extraordinary Communities That Arise in Disaster
Hell and High Water: Global Warming--the Solution and the Politics--and What We Should Do
The Worst Hard Time: The Untold Story of Those Who Survived the Great American Dust Bowl
The Tipping Point
Three Cups of Tea: One Man's Mission to Promote Peace... One School at a Time
The Upside of Down: Catastrophe, Creativity and the Renewal of Civilization
Out of Poverty: What Works When Traditional Approaches Fail
The Little Ice Age: How Climate Made History, 1300-1850
Confessions of an Eco-Sinner: Tracking Down the Sources of My Stuff
Deep Economy: The Wealth of Communities and the Durable Future
The Geography of Bliss: One Grump's Search for the Happiest Places in the World


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